At the top of the valve there are keepers. They are a collet style part, like a cone. They get wedged into their seat by the spring and interface with the valve to pull it up after the cam pushes it down.What are Loose keepers ?
Regular inspection of the valve train and proper lubrication are a good idea. Definitely replace them any time you remove the valves. Also replace the head gasket if you remove the valves. Could you get by reusing keepers or a head gasket? Maybe. Is it worth the risk? In my opinion, no.so replacing them is a good idea?